[quote name='mcgraham' post='261371' date='Aug 13 2008, 10:07 AM']Whenever I meet someone who clutches the neck like you've described, I demonstrate this...
Situation 1) I place my hand on the neck as you've described, with the thumb anchored around the top side of the neck, then show the other player how many frets I can reach at full stretch whilst keeping that thumb anchored. You'll get 2-3 max, depending on where you are on the neck (around the 7th fret say?).
Situation 2) I switch to thumb behind the neck, and show how many frets I can reach with my thumb behind the neck, usually 4 or 5 depending on where I am on the neck (around the 7th fret again).
I then get them to try it; I've not encountered anyone who doesn't acknowledge at least the ergonomic benefits. Keeping the thumb behind the neck rather than anchored on top of it will help relieve tension in your playing, will give you greater stretch along the freboard, as well as making it easier to stretch across it.
Mark[/quote]
Great way of demonstration! But...
If you grab your bass near the 1st fret, you can get a (realy near or) same amount of stretch with your hand around. As far as I know an even more important thing to mind is the placement of your elbow!
This might sound silly but people tend to put their elbow inside near their body where they should extend it more to match a less angled line (straight would be overworking it) with their wrists, and then you will also notice you can reach more frets. Usually my thumb is opposite to my ring- or middlefinger.